Vulnerability · Published Sep 25, 2026 · Assigned by php
CVE-2026-91768IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcmp 12 bytes)
Medium 6.5
In plain English
A medium-severity security flaw in PHP from PHP Group. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.4%top 68.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
The IPv6 branch of the FastCGI client access check compares only the first 12 bytes of a 16-byte IPv6 address, so listen.allowed_clients matches on a /96 prefix instead of the exact address. An attacker who can source an address sharing the first 96 bits with an allowed one passes the check and reaches the FastCGI endpoint.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | apcu-panel | 5.1.18-1.module_el8.6.0+2750+78feabcb | ALSA-2026:87080 |
| AlmaLinux:8 | libzip | 1.6.1-1.module_el8.6.0+3239+bedf0508 | ALSA-2026:87080 |
| AlmaLinux:8 | libzip | 1.6.1-1.module_el8.6.0+2750+78feabcb | ALSA-2026:87080 |
| AlmaLinux:8 | libzip | 1.6.1-1.module_el8.10.0+3935+28808425 | ALSA-2026:87080 |
| AlmaLinux:8 | libzip-devel | 1.6.1-1.module_el8.6.0+2750+78feabcb | ALSA-2026:87080 |
| AlmaLinux:8 | libzip-devel | 1.6.1-1.module_el8.10.0+3935+28808425 | ALSA-2026:87080 |
| AlmaLinux:8 | libzip-devel | 1.6.1-1.module_el8.6.0+3239+bedf0508 | ALSA-2026:87080 |
| AlmaLinux:8 | libzip-tools | 1.6.1-1.module_el8.10.0+3935+28808425 | ALSA-2026:87080 |
| AlmaLinux:8 | libzip-tools | 1.6.1-1.module_el8.6.0+3239+bedf0508 | ALSA-2026:87080 |
| AlmaLinux:8 | php | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-bcmath | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-cli | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-common | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-dba | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-dbg | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-devel | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-embedded | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-enchant | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-ffi | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-fpm | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-gd | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-gmp | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-intl | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-json | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-ldap | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-mbstring | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-mysqlnd | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-odbc | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-opcache | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-pdo | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-pear | 1:1.10.13-1.module_el8.10.0+3935+28808425 | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-apcu | 5.1.18-1.module_el8.10.0+3935+28808425 | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-apcu | 5.1.18-1.module_el8.6.0+2750+78feabcb | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-apcu-devel | 5.1.18-1.module_el8.6.0+2750+78feabcb | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-apcu-devel | 5.1.18-1.module_el8.10.0+3935+28808425 | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-rrd | 2.0.1-1.module_el8.6.0+2750+78feabcb | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-rrd | 2.0.1-1.module_el8.6.0+3239+bedf0508 | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-rrd | 2.0.1-1.module_el8.10.0+3935+28808425 | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-xdebug | 2.9.5-1.module_el8.6.0+3239+bedf0508 | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-xdebug | 2.9.5-1.module_el8.6.0+2750+78feabcb | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-zip | 1.18.2-1.module_el8.6.0+2750+78feabcb | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-zip | 1.18.2-1.module_el8.10.0+3935+28808425 | ALSA-2026:87080 |
| AlmaLinux:8 | php-pecl-zip | 1.18.2-1.module_el8.6.0+3239+bedf0508 | ALSA-2026:87080 |
| AlmaLinux:8 | php-pgsql | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-process | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-snmp | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-soap | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-xml | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| AlmaLinux:8 | php-xmlrpc | 7.4.33-8.module_el8.10.0+4321+cf5fd4bb | ALSA-2026:87080 |
| Alpine:v3.22 | php82 | 8.2.35-r0 | ALPINE-CVE-2026-91768 |
| Alpine:v3.22 | php83 | 8.3.36-r0 | ALPINE-CVE-2026-91768 |
| Alpine:v3.23 | php83 | 8.3.36-r0 | ALPINE-CVE-2026-91768 |
| Alpine:v3.24 | php83 | 8.3.35-r0 | ALPINE-CVE-2026-91768 |
| Alpine:v3.22 | php84 | 8.4.27-r0 | ALPINE-CVE-2026-91768 |
| Alpine:v3.23 | php84 | 8.4.27-r0 | ALPINE-CVE-2026-91768 |
| Alpine:v3.24 | php84 | 8.4.26-r0 | ALPINE-CVE-2026-91768 |
| Alpine:v3.23 | php85 | 8.5.12-r0 | ALPINE-CVE-2026-91768 |
| Alpine:v3.24 | php85 | 8.5.11-r0 | ALPINE-CVE-2026-91768 |
| Debian:12 | php8.2 | 8.2.34-1~deb12u1 | DEBIAN-CVE-2026-91768 |
| Debian:13 | php8.4 | 8.4.26-1~deb13u1 | DEBIAN-CVE-2026-91768 |
| Debian:14 | php8.4 | 8.4.26-1 | DEBIAN-CVE-2026-91768 |
| Rocky Linux:8 | libzip | 0:1.6.1-1.module+el8.10.0+1604+6558efc7 | RLSA-2026:87080 |
| Rocky Linux:8 | libzip | 0:1.6.1-1.module+el8.10.0+1912+72767185 | RLSA-2026:87080 |
| Rocky Linux:8 | php | 0:7.4.33-8.module+el8.10.0+40393+c071e357 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pear | 1:1.10.13-1.module+el8.10.0+1605+02e07af7 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pear | 1:1.10.13-1.module+el8.10.0+1912+72767185 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pear | 1:1.10.13-1.module+el8.10.0+1604+6558efc7 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pecl-apcu | 0:5.1.18-1.module+el8.10.0+1604+6558efc7 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pecl-apcu | 0:5.1.18-1.module+el8.10.0+1912+72767185 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pecl-rrd | 0:2.0.1-1.module+el8.10.0+1604+6558efc7 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pecl-rrd | 0:2.0.1-1.module+el8.4.0+414+2e7afcdd | RLSA-2026:87080 |
| Rocky Linux:8 | php-pecl-rrd | 0:2.0.1-1.module+el8.10.0+1912+72767185 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pecl-xdebug | 0:2.9.5-1.module+el8.10.0+1912+72767185 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pecl-xdebug | 0:2.9.5-1.module+el8.10.0+1604+6558efc7 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pecl-zip | 0:1.18.2-1.module+el8.10.0+1604+6558efc7 | RLSA-2026:87080 |
| Rocky Linux:8 | php-pecl-zip | 0:1.18.2-1.module+el8.10.0+1912+72767185 | RLSA-2026:87080 |
| Ubuntu:22.04:LTS | php8.1 | 8.1.2-1ubuntu2.27 | UBUNTU-CVE-2026-91768 |
| Ubuntu:22.04:LTS | php8.1 | 8.1.2-1ubuntu2.27 | USN-8936-1 |
| Ubuntu:24.04:LTS | php8.3 | 8.3.6-0ubuntu0.24.04.12 | USN-8936-1 |
| Ubuntu:24.04:LTS | php8.3 | 8.3.6-0ubuntu0.24.04.12 | UBUNTU-CVE-2026-91768 |
| Ubuntu:26.04:LTS | php8.5 | 8.5.4-0ubuntu1.4 | USN-8936-1 |
| Ubuntu:26.04:LTS | php8.5 | 8.5.4-0ubuntu1.4 | UBUNTU-CVE-2026-91768 |
| Ubuntu:26.10 | php8.5 | 8.5.9-0ubuntu2 | USN-8936-1 |
| Ubuntu:26.10 | php8.5 | 8.5.9-0ubuntu2 | UBUNTU-CVE-2026-91768 |
Affected products (as reported)
Weakness: CWE-1023 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N